BushidoD20TheoryResultionSystems

Ref: BushidoD20

Basic Resultions Systems

How it works

The systems are basically closer than they seam as you can convert from a target system to a roll under system with the follow equations

The basic Bushido system is:

Skill_BCS := ( Attr_Value + Skill_Value ) / 5

Skill_MCS := Skill_BCS + Proffesional_Bonus + Other_Bonuses

Skill_MCS + Situation_Modifiers >= (Low)d20

and d20 is

Skill_Mod := Attr_Value + Skill_Value + Char_Modifiers

Skill_Modifier + (High)d20 => Target DC + Situation_Modifiers

To convert you need to know that when you inverse the probabilities from a high d20 to a low d20 you do it by subtracting from 21 ie

(High)d20 == 21 - (Low)d20

21 - (High)d20 == (Low)d20

So that the Bushido resolution system can be rewritten

Skill_MCS + Situation_Modifiers >= (Low)d20

Skill_MCS + Situation_Modifiers >= 21 - (High)d20

Skill_MCS + (High)d20 >= 21 - Situation_Modifiers

A 1st level Bushi will have a MCS in combat about 15 and a 1st level d20 Fighter will have a To Hit of (Str +3, Attack +1, Weapon Prof. +1) = +5 (ie 10 difference).

If you extend this, 6th level Bushi will have a MCS of about 26 and 3 attacks per round. An 11th level Fighter will have a Attack of +16 and 3 attacks around. (again 10 difference). Hence I am lead to the follow very crude conclusions.

1. you can convert from a Bushido MCS to d20 skill value by subtracting 10, and via a versa by adding 10.
2. a d20 characters level is equal to about double a Bushido characters.

• Yes this is not right, a 11th level Fighter would have +16, +11, +6 but he would also most likely have a whole set of magic items or other feats that would attually improve its odds. So for the moment this is an educated guess it might be nessary to do some statistical computations to get the value correct.

Using the d20 System

The basic roll system becomes:

( Skill_MCS - 10 ) + (High)d20 >= 11 - Situation_Modifiers

Situation Modifiers are themselves sensity to the side of the equation they are on, so if you invert the Bushido ones then they are the same way round as the d20 system.

Armour Class are close to the same ranges even if they are based on a slightly different system. By following the same logic you end up with adding 10 to the AC. Which is the same as d20 anyway.

( Skill_MCS - 10 ) + (High)d20 >= 11 + Bushido_AC

Remeber that the -10 would be predone by the player on there character sheet. And the 10 modifier is in fact the default target in the d20 system and all the TN assume it.

For Example, assume a character has a Climb MCS of 18 that means in the d20 system they have a Skill Value of +8. If they have to make a standard TN climb of 15 that means they roll d20+8 to beat or equal 15 in the standard way.

Using the Bushido System

The basic roll system becomes:

( Skill_Modifier + 10 ) + Situation_Modifiers >= (Low)d20

and attack

d20_AC := d20_AC_Mods + 10

( Skill_Modifier + 10 ) - ( d20_AC - 10 ) >= (Low)d20

( Skill_Modifier + 10 ) - d20_AC_Mods >= (Low)d20

Remeber that the +10 would be predone by the player on there character sheet.

For example, assume a character had a Climb of +6, that means there Climb MCS would be 16. If they climb was a -5 difficulty they would need to roll under 11 to succeed.